Abstract Hopelessness is associated with a 3.4 times increased risk of mortality or nonfatal myocardial infarction in patients with ischemic heart disease (IHD), independent of depression. Hopelessness has been identified in 27?52% of patients with IHD and can persist for up to 12 months after hospital discharge. Hopelessness, a negative outlook and sense of helplessness toward the future, can be a temporary response to an event (state) or a habitual outlook (trait). Hopelessness is associated with decreased physical functioning and lower physical activity (PA) levels in individuals with IHD. Low levels of PA independently contribute to increased death and adverse events in patients with IHD. Rates of PA in IHD patients continue to be unacceptably low in both hospital-based cardiac rehabilitation and home settings. Hopelessness frequently compounds this issue. The links among hopelessness, PA, and mortality and morbidity for patients with IHD remain unknown. While research has investigated strategies to increase PA among IHD patients in general, we are the only group to design an intervention to promote PA specifically in hopeless IHD patients. Our work, based on Self Determination Theory and Cohen's Stress and Coping Social Support Theory, has shown feasibility and preliminary efficacy for a motivational intervention that integrates social support from both the patient's nurse and significant other to promote increased PA. The purpose of this randomized controlled trial is to establish the effectiveness of our 6-week mHealth intervention (Heart Up!) to promote increased PA in hopeless patients with IHD. We will enroll 225 hopeless IHD patients from a large community teaching hospital in the Midwest. Patients will be randomized (75 per group) to one of three groups: 1) motivational social support (MSS) from a nurse, 2) MSS from a nurse with additional significant other support (SOS), or 3) attention control (AC). Data will be collected at baseline, 8 and 24 weeks using an accelerometer for PA and valid and reliable instruments of physical and emotional health and behaviors. The specific aims are to: 1) test the effectiveness of 6 weeks of MSS and MSS with SOS on increasing mean minutes per day of moderate to vigorous PA, measured by an ActiGraph accelerometer; 2) determine the effects of change in minutes per day of moderate to vigorous PA on state hopelessness, measured by the State-Trait Hopelessness Scale; and 3): determine if social support (measured by the ENRICHD Social Support Inventory) and motivation (measured by the Exercise Self- Regulation Questionnaire) mediate the effects of the Heart Up! intervention on PA. The findings from this study could transform care for IHD patients who are hopeless by promoting self-management of important PA goals that can contribute to better health outcomes. This proposal supports NINR's investment in self-management to improve the quality of life for individuals with chronic illness.